This application claims priority to Republic of Korea Patent Application No.: 2000-40968 filed Jul. 18, 2000.
The present invention relates generally to a ceramic deodorizer, in particular, to a ceramic deodorizer comprising magnesium and calcium phosphate compounds being environmentally safe, capable of effectively removing various malodorous components.
Generally, conventional methods for removing malodorous components comprise a sensory deodorization method using a masking agent and a neutralizing agent, a physical deodorization method using a wet washing and an adsorption, a biological deodorization method by use of microorganisms and a chemical deodorization method using precious metals.
Among said methods, the sensory method mainly using the masking agent cannot fundamentally remove malodorous components. The wet washing of the physical method is caused to produce wastewater and to increase maintenance costs. Also, the simple adsorption using an active carbon and charcoal is initially effective but adsorption ability is reduced as time goes by and the adsorbed malodorous components are easily desorbed by a change of surrounding environments. The biological method has disadvantages of requiring expensive facilities and maintenance of temperature and humidity ranges. The chemical method has used catalysts of expensive precious metals such as gold (Au), platinum (Pt), palladium (Pd), rhodium (Rd) and so on. However, the chemical method has recently begun using inexpensive metal oxides. For example, Korean Laid-open Pat. Appln. No. 98-013721 discloses a method for preparing a deodorization filter for refrigerator using metallic salt oxidants as adsorbents. Also, Korean Laid-open Pat. Appln. No. 99-016787 refers to a deodorization filter for refrigerator using catalysts such as copper, manganese and gold and an active carbon as adsorbent, while Korean Laid-open Pat. Appln. No. 99-0071045 refers to a deodorization filter for refrigerator using as adsorbent, honeycomb-shaped activated charcoal in which manganese dioxide and copper oxide and artificial enzyme catalysts are impregnated at certain proportions. But the metal oxides irritate skin and may be harmful to the human body. Accordingly, the oxides cannot be used as the deodorizer for home use owing to a safety problem.
To alleviate the problems, in recent years, calcium phosphate compounds, being harmless to the human body, have been used as deodorizers. Among the calcium phosphate compounds, non-stoichiometric structure of appetite (Ca10-xHx(PO4)6(OH)2-x) or tricalcium phosphate (TCP, Ca3(PO4)2) is mainly used. Japanese Laid-Open Pat. Appln. No. 5309266 discloses an apatite hydroxide having excellent deodorization effect versus malodorous lower fatty acid occurring in food wastes. Additionally, in order to improve an deodorization ability versus other malodorous components in addition to lower fatty acids, Japanese Laid-Open Pat. Appln. No. 10118167 discloses that calcium phosphate compound is added with iron, copper, zinc, nickel and aluminum for use as a deodorizer, while Japanese Laid-open Pat. Appln. No. 8126690 discloses that silver is ion-exchanged or adsorbed in the calcium phosphate compound for use as a deodorizer. In addition, Japanese Laid-Open Pat. Appln. No. 2237639 discloses that Zn2+, Cu2+, Fe2+, Co2+, Ni2+, Sn2+, Pb2+ and Cd2+are ion-exchanged in the calcium phosphate compounds for use as a deodorizer. U.S. Pat. No. 4,988,505 discloses a deodorizer which comprises a colloidal antimony pentoxide that is effective to deodorize a basic gas, an acidic gas, and an organic solvent gas. But the metal oxides, metal ions and colloidal antimony pentoxide have toxic properties so that a danger exists to the human body and environment, and their deodorization ability versus various malodorous components is limited.
Accordingly, an object of the present invention for alleviating the problems as described above is to provide a deodorizer composition, that is environmentally safe, harmless to the human body, and capable of removing malodors from various sources.
For the invention, the calcium phosphate compound may be selected from the group consisting of apatite, monocalcium phosphate (CaHPO4), tricalcium phosphate (TCP), octacalcium phosphate (OCP), and mixtures thereof.
In another aspect of the present invention, a deodorizer composition comprising a mixture of at least one magnesium compound and at least one calcium phosphate compound is provided.
In still another aspect of the present invention, a ceramic deodorizer prepared by heating the compositions is provided.
According to another aspect of the present invention, is provided a process for preparing the deodorizer composition, which comprises the steps of:
providing a solution of magnesium nitrate in phosphoric acid solution;
adding calcium hydroxide to the solution to give a mixture; and
allowing the mixture to stand for several hours.
The composition can be heat treated to give the ceramic deordorizer.